Rac-1-palmitoyl-2-linoleoyl-3-acetylglycerol is one of components of deer antler, and is known as one of the most active components having the growth-stimulating effects of hematopoietic stem cells and megakaryocytes which can be obtained from chloroform extracts of the deer antler (Korean Patent No. 10-0283010). In Korean Patent No. 10-0291743, two methods for preparing the rac-1-palmitoyl-2-linoleoyl-3-acetyl glycerol, (a) a method of synthesizing the compound from glycerol and (b) a method of using acetolysis of phosphatidylcholine are disclosed. However, the reaction of method (a) has no regioselectivity. Thus, from the reaction product of glycerol and palmitic acid, 1-palmitoylglycerol should be separated by using a column chromatography. The separated 1-palmitoylglycerol is acetylated and separated again by using a column chromatography. Then, a linoleoylation reaction is carried out for the above reaction product and a separation step using a column chromatography is again carried out to produce the target compound of rac-1-palmitoyl-2-linoleoyl-3-acetylglycerol. Since the reaction of method (a) has no regioselectivity, the reaction product of each reaction step should be separated and purified by using a column chromatography, and the overall yield of the target compound is very low (about 3.21% from glycerol). Furthermore, the reaction of method (a) utilizes Steglich esterification using N,N′-dicyclohexyl carbodiimide (DCC), and a side reaction, in which an acyl group is migrated in an adduct of DCC and carboxylic acid, may occur. To reduce the side reaction, the expensive catalyst 4-dimethylaminopyridine (DMAP) should be used in the amount of more than one equivalent. However, the side reaction cannot be completely suppressed, dicyclohexylurea is formed as a by-product, and it is difficult to completely remove the by-product by a filtration and an extraction.
In order to regioselectively synthesize glycerol derivative having ester groups of different fatty acids at 1 and 2-positions of glycerol and having acetyl group at 3-position of glycerol, the following process is generally carried out. First, an ester group is regioselectively introduced into 1-position of glycerol. Then, after protecting hydroxyl group of 3-position of glycerol which is more reactive than hydroxyl group of 2-position of glycerol, and ester group should be introduced into 2-position of glycerol. The process can regioselectively introduce ester groups into 1, 2 and 3-positions of glycerol. However, when removing the protecting group at 3-position of glycerol to introduce an ester group to the 3-position, there is a problem that the ester group of 2-position of glycerol is migrated to the 3-position of glycerol (J. Org. Chem., 52 (22), 4973˜4977, 1987). Also, this method has drawbacks in that a protecting group should be introduced and the protecting group should be removed by which the overall reaction requires several reaction steps.
However, when a glycerol derivative having an ester group of fatty acid at 1-position of glycerol and acetyl group at 3-position of glycerol, for example, 1-palmitoyl-3-acetyl glycerol represented by the following Formula 1 is used to synthesis 1-palmitoyl-2-linoleoyl-3-acetylglycerol, the above-mentioned drawbacks can be eliminated. Therefore, there are demands for preparing racemic or optically active and pure 1-palmitoyl-3-acetylglycerol.
